1. Field of the Invention
The present invention generally relates to a magnetic disk storage device with floating type magnetic heads. The present invention also relates to a return mechanism used in such a magnetic disk storage device for automatically positioning heads to non-data area.
2. Prior Art
In a magnetic disk storage device with a floating type magnetic head, the floating heads are held slightly above the disk surface by air flow resulting from the rotation of the magnetic disk. In that position, data is written to and read from the magnetic disk.
In such a magnetic disk storage device, after the input or output step is finished, the rotation of the magnetic disk is stopped. Then, the deceleration heads lower and come into contact with the surface of the decelerating magnetic disk.
For this reason, directly after starting the magnetic disk and directly before the magnetic disk stops turning, the surface of the disk may receive wear or mechanical injury from the descending head as the air flow becomes too weak to maintain the magnetic head above the disk surface. Furthermore, because the head comes in to contact with the disk in a data area, loss of data may occur due to any injury that occurs to the disk surface.
In addition, when the magnetic disk storage device is moved or bumped, bouncing of the head on the disk surface may occur with resulting disk damage and possible data loss.
In order to solve these problems, a return mechanism for magnetic disk storage devices was proposed recently. The return mechanism automatically positions heads to non-data area which will hereinafter be abbreviated an "auto-return mechanism".
Such an auto-return mechanism comprises a spring which connects the housing of the storage device and the carrier mounted to the magnetic head. The spring acts on the magnetic head to move and maintain it outside of the data area when the electric power is off. However, in a magnetic disk storage device with the above described auto-return mechanism, several problems remain.
The longer the spring extends, the stronger the spring force becomes. That is, the spring force varies due to the position of the head. Additionally, if the head is moved at high speed, the spring causes the head to vibrate. Consequently, the spring force undesirably effects the position of the carrier during head positioning operations, so that the position of the head is difficult to control.
In addition, the starting position of the head on the magnetic disk, that is track No. 0, from where the head starts to read and/or write data is important to assure correct data transfer. However, the starting position of the head is easily affected by a dimension error in manufacturing the carrier and mounting the carrier to the magnetic disk storage device. Therefore, an adjusting mechanism for adjusting the starting position of the head has been required.